Earth Syst. Sci. Data, 8, 89–103, 2016 www.earth-syst-sci-data.net/8/89/2016/ doi:10.5194/essd-8-89-2016 © Author(s) 2016. CC Attribution 3.0 License. Survey of the terrestrial habitats and vegetation of Shetland, 1974 – a framework for long-term ecological monitoring Claire M. Wood1 and Robert G. H. Bunce2 1Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, LA1 4AP, UK 2Estonian University of Life Sciences, Kreuzwaldi 5, 51014 Tartu, Estonia Correspondence to: Claire M. Wood ([email protected]) Received: 12 October 2015 – Published in Earth Syst. Sci. Data Discuss.: 23 October 2015 Revised: 3 February 2016 – Accepted: 14 February 2016 – Published: 25 February 2016 Abstract. A survey of the natural environment was undertaken in Shetland in 1974, after concern was ex- pressed that large-scale development from the new oil industry could threaten the natural features of the islands. A framework was constructed by the Institute of Terrestrial Ecology on which to select samples for the sur- vey. The vegetation and habitat data that were collected, along with the sampling framework, have recently been made public via the following doi:10.5285/06fc0b8c-cc4a-4ea8-b4be-f8bd7ee25342 (Terrestrial habitat, vegetation and soil data from Shetland, 1974) and doi:10.5285/f1b3179e-b446-473d-a5fb-4166668da146 (Land Classification of Shetland 1974). In addition to providing valuable information about the state of the natural environment of Shetland, the repeatable and statistically robust methods developed in the survey were used to underpin the Countryside Survey, Great Britain’s national long-term integrated environmental monitoring pro- gramme. The demonstration of the effectiveness of the methodology indicates that a repeat of the Shetland survey would yield statistics about ecological changes in the islands, such as those arising from the impacts of the oil industry, a range of socio-economic impacts, and perhaps climate change. Currently no such figures are available, although there is much information on the sociological impacts, as well as changes in agriculture. 1 Introduction and geomorphology were also undertaken around the same time as part of a larger integrated survey (Milner, 1975). The specific objectives of the terrestrial component were In the 1960s, the discovery of North Sea oil off the coast as follows: of Shetland, Scotland, meant that the islands had to face the prospect of large-scale development to accommodate the in- i. To assess the range of variation within the vegetation of frastructure surrounding the industry. In the early 1970s, con- Shetland and to provide a user guide to defined types. cern was expressed by the county council that such develop- ii. To provide a structural basis for monitoring future ment would threaten the natural features of Shetland, such change in the vegetation (Bunce, 1975). as landscape and wildlife. Accordingly, in 1974, a survey was commissioned by the Nature Conservancy Council (now The Shetland Survey was also a stage in the development Scottish Natural Heritage in Scotland) and organised by the by ITE of the methodology of strategic ecological survey, as Institute of Terrestrial Ecology (ITE) (now part of the Cen- described by Sheail and Bunce (2003). tre for Ecology and Hydrology) to assess the natural envi- The vegetation survey was undertaken using standardised ronment of the islands. Although the terrestrial habitats and methods outlined by Bunce and Shaw (Bunce and Shaw, vegetation survey are the focus of this paper, assessments of 1973; Bunce, 1974). In order to randomly sample Shetland freshwater and littoral habitats, sea-bird populations, geology in a strategic way, the islands were stratified into a set of 16 Published by Copernicus Publications. 90 C. M. Wood and R. G. H. Bunce: Survey of the terrestrial habitats and vegetation of Shetland, 1974 relatively homogenous areas (strata, or “land classes”). Sam- with the average monthly temperature ranging from approx- pling locations were randomly selected from within each of imately 3 ◦C (February) to 12 ◦C (July) (Met Office, 2015). these strata, giving a total of eighty 1 km2 sampling units, The exposed situation of the islands means they are subject each containing up to 16 200 m2 sampling plots. Records to high winds, with about 40 days of gales per year. The rain- of plant species, soils, habitat types and major biota present fall is not extreme (around 1124 mm per annum) (Met Office, were collected. 2015) but is distributed throughout the year, so that damp and Prior to the survey, a two-day training course was held drizzly days are common. to familiarise the surveyors with the detailed field protocols. Additionally, all survey teams were initially accompanied by 3 The survey in context a supervisor, and regular visits into the field were made by the project leader to ensure consistency and quality in data The survey of Shetland is relevant on a number of levels. recording according to criteria laid out in the field handbook Firstly, the data are of local interest to anyone concerned with (Bunce, 1974). the ecology and land use of the islands. Should a resurvey At the time, the statistical sampling methods used were be undertaken, potential changes in vegetation could be as- generally not widely used as a method for ecological mon- sessed against a range of local and national socio-economic itoring, and this was one reason why the results were not changes occurring since the 1970s. Secondly, the data are of reported publicly at the time. The other factor was that the a wider global significance when applied to the potential ef- senior author also had other commitments. Therefore, this is fects of global climate change. the first time that the data and results have been made widely Additionally, as described in Sect. 4, the design of the available. There have been many changes in the islands since methodology itself is of importance, having been applied to the survey, both socio-economic and environmental, and the national monitoring schemes in Britain, and beyond. data provide a unique opportunity to explore the changes that have taken place in the vegetation, should a repeat survey be 3.1 The survey in a local context undertaken. In addition to the survey yielding an interesting set of data At the time of the survey, a review of the available ecological in itself, the methodological framework for the survey even- knowledge regarding Shetland was made by Goode (1974). tually developed into the largest long-term ecological moni- Attention was drawn to the major gaps that were present, toring project in Britain, the Countryside Survey (CS) (Carey few of which have since been filled. Insufficient informa- et al., 2008). CS started in 1978 and was most recently un- tion and detail were available on the islands in McVean and dertaken in 2007. Ratcliffe (1962). Birse (1974) provided a general account of Sullom Voe and Barkham (1971) and Allot (1971) described aspects of Foula. The specialised habitats of the fell fields 2 Shetland and the serpentine are also summarised by Spence (1974). Most of the published work has concentrated on two spe- The Shetland Islands cover an area of about 1400 km2 and cialised habitats – the Fell fields of Ronas Hill and the ser- consist of over a hundred islands and islets, of which about pentine habitats of Unst (Spence, 1974). The small areas of 15 are inhabited. The southernmost tip of the largest island relict scrub, mainly on ungrazed islands in the lochs, are also lies over 160 km north-west of John o’ Groats. Lying at the described by the same author. northern limit of the Britain, the isles have considerable bio- The only major paper on the overall vegetation is by geographic interest. Roper-Lindsay and Say (1986), who used phytosociologi- The islands are geologically diverse, with the main rock cal methods to describe 17 associations in relation to British, types being metamorphic, including Caledonian schists, continental and Scandinavian communities. They found dif- gneisses and quartzites. There are also areas of Old Red ficulties in determining discrete associations because of fac- Sandstone. tors such as intensive land use and the maritime influence. The inland topography is gentle, with wide, shallow val- Hence, the present study is the first to provide a complete leys. Around the coast, there are sheer cliffs, and numerous overview of the vegetation of the islands. sheltered inlets or “voes”. There are few trees on the islands, By contrast, the flora of Shetland is relatively well known, and extensive areas are covered in peat, especially on the for example Scott and Palmer (1987) for vascular plants and Mainland and the northern island of Yell. The soils on Shet- Dalby and Dalby (2005) for lichens and as summarised in land are generally poor, with the most fertile land being on the BSBI Atlas of the British and Irish Flora (Preston et al., the sandstone in the south, where the main crofting districts 2002), which is due to be updated in 2020, and the original are located. bryophyte atlas published in 1991–1994 (Hill et al., 1991) but The general climate is mild, moist and windy. Although recently repeated (Blockeel et al., 2014). Also, Hill and Pa- minor changes may be discerned over time (see Sect. 3.3), ton (1976) have reported on the saxicolous bryophytes. The there is little variation in temperature through the year, phyto-geographic relationships of the Shetland flora have Earth Syst. Sci. Data, 8, 89–103, 2016 www.earth-syst-sci-data.net/8/89/2016/ C. M. Wood and R. G. H. Bunce: Survey of the terrestrial habitats and vegetation of Shetland, 1974 91 been widely discussed, as summarised by Goode (1974). Al- habitats and species of conservation value are often found in though some species differ in their ecology because of the crofting communities; therefore these are now under threat northern location, the species complement is closely related (Scottish Rural Development Programme, 2016).